1. Field of the Invention
The present invention relates to an electric fuel pump for an automobile or the like, and more particularly, to an electric fuel pump with improved mounting structure of choke coils required for suppressing noise to a radio or a stereo assembled in the automobile.
2. Description of the Prior Art
FIG. 4 is a sectional view of a conventional electric fuel pump including choke coils for noise suppression, and FIG. 5 is a sectional plan view taken along the line V--V in FIG. 4. In FIGS. 4 and 5, 1 a cylindrical motor housing 1 of magnetic material also serves as a pump housing, and a cover 2 is fixed to the upper end of the housing. The cover 2 to retains a motor 3 in the housing and defines a fuel outlet port 4. A bracket 5 defining a pump chamber and a pump cover 6 including a fuel suction port 13 are engaged with the lower edge of the motor housing 1. Interposed between the bracket 5 and the pump cover 6 is an impeller 8 fixed for co-rotation to a shaft 7 of the motor 3. A commutator 9 is mounted on the motor shaft 7, and a pair of brushes 10 are pressure-welded to the side surface of the commutator 9 symmetric to the central axis of rotation thereof. The brushes 10 are held by brush holders 11 respectively, and connected with pigtails 12 for supplying power.
Lead wires 14 for power supply extend into the motor housing 1 through the cover 2, such that the forward ends thereof are connected with terminal boards 15 fixed on the bracket 5 respectively. Between the terminal boards 15 and the pigtails 12, choke coils 16 are respectively connected to eliminate electrical noise generated by rectification. In further detail, upwardly extending projections 17a and 17b are provided on the bracket 5 to respectively hold the choke coils 16, whose one-side ends are connected to the forward ends of the lead wires 14 respectively on the terminal boards 15 while the other ends are connected to the pigtails 12 on L-shaped bent portions 18 of the brush holders 11 respectively, to define electrical paths.
By external power supplied to the lead wires 14, the commutator 9 is supplied with power through the choke coils 16 and the brushes 10, whereby the shaft 7 of the motor 3 is rotated, resulting in rotation of the impeller 8 fixed to the shaft 7. Thus, fuel (liquid) is sucked through the suction port 13 provided on the pump cover 6 and passes through the housing interior defined by the motor housing 1, the cover 2 and the pump cover 6 to be discharged from the outlet port 4 formed in the cover 2.
In the aforementioned conventional electric fuel pump, the structure for holding the choke coils 16 and the forward ends of the lead wires 14 is relatively weak. Consequently, the choke coils 16 may be displaced or disconnected from the forward ends of the lead wires 14 by vibration or shock applied to the fuel pump.
Further, since conductive parts such as the forward ends of the lead wires 14, ends of the choke coils 16 and the terminal boards 15 are exposed, the same may be in contact with the motor housing 1 of magnetic material. Thus, improvement in insulativity is required.
In addition, assembly is difficult since the other ends of the choke coils 16 must be connected with the pigtails 12 after fixing the terminal boards 15 on the bracket 5 and mounting the choke coils 16.